Anti-Separating Structure of Sensing Magnet For EPS Motor

ABSTRACT

Disclosed is an anti-separating structure of a sensing magnet for EPS motor, the structure being a coupling structure between the sensing magnet and a plate of the EPS motor, the structure including a disk-shaped plate formed with a magnet accommodation unit protrusively formed near at a rotation shaft, a ring-shaped sensing magnet centrally formed with a through hole having a diameter corresponding to the magnet accommodation unit, and magnet grip units each formed at a predetermined gap along a circumferential surface of the magnet accommodation unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/552,226, filed Jul. 18, 2012, which claims the benefit under 35U.S.C. §119 of Korean Patent Application Nos. 10-2011-0072976, filedJul. 22, 2011; 10-2011-0073666, filed Jul. 25, 2011; 10-2011-0073667,filed Jul. 25, 2011; and 10-2011-0081038, filed Aug. 16, 2011, which arehereby incorporated by reference in their entirety.

BACKGROUND

1. Field of the Invention

The present disclosure relates to a coupling structure b sing magnet anda plate of an EPS motor.

2. Discussion of the Related Art

Generally, almost every vehicle employs an electric power-assiststeering system. Such an electric power-assist steering system generatesan assist force based on the steering torque and the steering angle, soas to enhance the steering performance of the vehicle.

That is, a steering system that assists a steering force of a vehiclewith a separate power is used to enhance the motion stability of avehicle.

Conventionally, the auxiliary steering device uses hydraulic pressure,but an Electronic Power Steering (EPS) system adapted to transmit arotation output of an electric motor to a steering shaft via a speedreduction mechanism has been increasingly employed these days from aviewpoint of a reduction in engine load, a reduction in weight, anenhanced steering stability and a quick restoring force.

The EPS system is such that an Electronic Control Unit (ECU) drives amotor in response to steering conditions detected by a speed sensor, atorque angle sensor and a torque sensor to enhance a steering stabilityand provide a quick restoring force, whereby a driver can safely steer avehicle.

The EPS system is also such that a motor assists a torque manipulating asteering wheel to allow a driver to steer a vehicle with less power,where the motor employs a Brushless Direct Current (BLDC) motor.

The BLDC motors have been increasingly used because the brushless motorsare excellent in maintenance property, have a small size, and arecapable of generating a high torque. The BLDC motor generally forms anexterior look by coupling of housing and a cover member, an innercircumferential surface of the housing is provided with a stator, andthe stator is centrally formed with a rotor rotatably mounted inelectrical interaction with the stator. The rotor is rotatably supportedby a rotation shaft, and an upper surface of the rotation shaft isconnected by a steering shaft of a vehicle to provide a power assistingthe steering of the vehicle as mentioned above.

The cover member is formed therein with a PCB (Printed Circuit Board)mounted with a sensing device provided in a magnetic device, where thesensing device detects a magnetic force of a sensing magnet rotatablymounted with the rotor, whereby a current position of the rotor can bechecked. Generally, the sensing magnet is fixed to an upper surface of aplate mounted at an upper side of the rotor using an adhesive. In a casethe sensing magnet is magnetized to the plate, the position of the rotorcan be detected by coupling of the plate to the rotation shaft inresponse to a direction of magnetic field.

The coupling of the plate to the sensing magnet is performed using theadhesive as mentioned above. Thus, it is difficult to precisely controlthe adhesion process, and there is a possibility of the sensing magnetbeing separated. Particularly, in view of vehicular characteristicswhere environmental conditions vary, a coupling relation must bemaintained by a coupling force of the adhesive alone, and if a motor isused under an alternating conditions of high temperature and lowtemperature, or exposed under a high temperature for a long time, theadhesive force of the adhesive may decrease to generate a separation ofsensing magnet or a disablement of motor driving. This structuregenerates a difficulty in selecting a proper adhesive and an economicaldifficulty in selecting a high price adhesive, and poses a problem ofrequiring a further fine coating process of adhesive.

BRIEF SUMMARY

The present disclosure is directed to cope with the abovementionedproblems/disadvantages and it is an object of the present disclosure toprovide an improved anti-separating structure of a sensing magnet forEPS motor, capable of inhibiting a sensing magnet from separating evenin a case the sensing magnet is used under a high temperature for a longtime or under a temperature severely-changing environment condition byimproving a coupling structure between the sensing magnet and a plate.

Technical problems to be solved by the present disclosure are notrestricted to the above-mentioned description, and any other technicalproblems not mentioned so far will be clearly appreciated from thefollowing description by the skilled in the art.

In a general aspect of the present disclosure, there is provided ananti-separating structure of a sensing magnet for EPS motor, thestructure being a coupling structure between the sensing magnet and aplate of the EPS motor, the structure comprising: a disk-shaped plateformed with a magnet accommodation unit protrusively formed near at arotation shaft; a ring-shaped sensing magnet centrally formed with athrough hole having a diameter corresponding to the magnet accommodationunit; and magnet grip units each formed at a predetermined gap along acircumferential surface of the magnet accommodation unit.

Preferably, but not necessarily, the plate is coated with an adhesive ona surface opposite to the sensing magnet.

Preferably, but not necessarily, an outmost diameter of the sensingmagnet corresponds to a diameter of the plate.

Preferably, but not necessarily, the magnet grips are formed by caulkingat a predetermined gap along a circumference of the magnet accommodationunit.

Preferably, but not necessarily, the magnet grips are formed by caulkinga total of 12 positions of the circumference of the magnet accommodationunit at a 30-degree gap.

In another general aspect of the present disclosure, there is providedan anti-separating structure of a sensing magnet for EPS motor, thestructure being a coupling structure between the sensing magnet and aplate of the EPS motor, the structure comprising: a disk-shaped platecentrally inserted by a rotation shaft; a ring-shaped sensing magnethaving a through hole at a center coupled to an upper side of the plate;and magnet grips protruded toward the sensing magnet from the plate togrip the through hole of the sensing magnet.

Preferably, but not necessarily, the magnet grip includes a support ribprotruded toward an upper side of the plate, and a separation inhibitionunit surface-contacting an upper surface of the sensing magnet bybending a distal end of the support rib.

Preferably, but not necessarily, at least a pair of magnet grips isprovided, each magnet grip being symmetrically arranged relative to acenter of the plate to allow the support ribs to face each other.

Preferably, but not necessarily, an outmost diameter of the sensingmagnet corresponds to a diameter of the plate.

Preferably, but not necessarily, the plate is coated with an adhesive ona surface opposite to the sensing magnet.

In still another general aspect of the present disclosure, there isprovided an anti-separating structure of a sensing magnet for EPS motor,the structure being a coupling structure between the sensing magnet anda plate of the EPS motor, the structure comprising: a disk-shaped platecentrally inserted by a rotation shaft; a ring-shaped sensing magnethaving a through hole at a center coupled to an upper side of the plate;a magnet support rib protruded from the plate toward sensing magnet togrip a first support surface of the through hole at the sensing magnet;a holder member coupled to an upper side of the sensing magnet tosupport a second support surface provided at an ambience of the firstsupport surface; and a fixing unit fixing the holder member to theplate.

Preferably, but not necessarily, the fixing unit includes a fasteningmember coupled to a second through hole penetratively formed at theplate after passing through the first through hole penetratively formedat the holder member.

Preferably, but not necessarily, the fastening member includes any oneof a screw or a rivet.

Preferably, but not necessarily, the fixing unit includes a hookintegrally formed with the holder member and protrusively formed fromthe holder member toward the plate, and a hitching unit penetrativelyformed at a position corresponding to the hook of the plate.

Preferably, hut not necessarily, the second support surface isprotrusively formed horizontally across the first support surface towarda center of the sensing magnet.

Preferably, but not necessarily, the first and second support surfaces,each one pair and facing each other, are symmetrically formed based onthe center of the sensing magnet.

Preferably, but not necessarily, the second support surface is formedwith a slant surface of a predetermined area to allow surface-contactinga surface opposite to the holder member.

Preferably, but not necessarily, an outmost diameter of the sensingmagnet corresponds to a diameter of the plate.

Preferably, but not necessarily, the plate is coated with an adhesive ona surface opposite to the sensing magnet.

In still another general aspect of the present disclosure, there isprovided an anti-separating structure of a sensing magnet for EPS motor,the structure being a coupling structure between the sensing magnet anda plate of the EPS motor, the structure comprising: a disk-shaped platecentrally inserted by a rotation shaft; a ring-shaped sensing magnethaving a through hole at a center coupled to an upper side of the plate,formed with a main magnet at a position near to a periphery and formedwith a sub magnet at a position near to the through hole; a magnetsupport rib protruded from the plate toward sensing magnet to grip afirst support surface of the through hole at the sensing magnet; aholder member coupled to an upper side of the sensing magnet to supporta second support surface provided at an ambience of the first supportsurface; a fixing unit fixing the holder member to the plate; and anadhesive accommodation groove formed at a predetermined depth on asurface opposite to the plate of the sensing magnet and coated thereinwith an adhesive.

Preferably, but not necessarily, the fixing unit includes a fasteningmember coupled to a second through hole penetratively formed at theplate after passing through the first through hole penetratively formedat the holder member.

Preferably, but not necessarily, the fastening member includes any oneof a screw or a rivet.

Preferably, but not necessarily, the adhesive accommodation groove is soarranged as to inhibit a formed position of the main magnet frominterfering with a formed position of the sub magnet.

Preferably, but not necessarily, the adhesive accommodation groove isformed with a depth within 0.05 mm.

Preferably, but not necessarily, an outmost diameter of the sensingmagnet corresponds to a diameter of the plate.

The anti-separating structure of sensing magnet for EPS motor accordingto the present disclosure has an advantageous effect in that a sensingmagnet and a plate are physically formed and fixed using a plurality ofcaulking unit in addition to an adhesive, such that even if useenvironment of motor is inadequate, the sensing magnet and plate areinhibited from being separated to enhance a reliability of the motor.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the present disclosure and are incorporated in thepresent disclosure and constitute a part of this application, andtogether with the description, serve to explain the principle of thedisclosure. In the drawings:

FIG. 1 is a schematic cross-sectional view of an EPS motor according toan exemplary embodiment of the present disclosure;

FIG. 2 is an exploded perspective view of a sensing magnet and a platein FIG. 1 according to a first exemplary embodiment of the presentdisclosure;

FIG. 3 is a perspective view illustrating the plate and the sensingmagnet that are coupled;

FIG. 4 is an exploded perspective view of the sensing magnet and theplate of FIG. 1 according a second exemplary embodiment of the presentdisclosure;

FIGS. 5 and 6 are perspective views illustrating a state in which theplate and the sensing magnet of FIG. 4 are coupled;

FIG. 7 is a schematic cross-sectional view illustrating an EPS motoraccording to a third exemplary embodiment of the present disclosure;

FIG. 8 is an exploded perspective view of a sensing magnet and a plateaccording a third exemplary embodiment of the present disclosure;

FIG. 9 is a perspective view illustrating coupled state of FIG. 8;

FIG. 10 is a cross-sectional view taken along line A-A of FIG. 8;

FIG. 11 is an exploded perspective view of a sensing magnet and a plateaccording a fourth exemplary embodiment of the present disclosure;

FIG. 12 is a perspective view illustrating coupled state of FIG. 11;

FIG. 13 is a cross-sectional view taken along line B-B of FIG. 12;

FIG. 14 is an exploded perspective view of a sensing magnet and a plateaccording a fifth exemplary embodiment of the present disclosure;

FIG. 15 is a perspective view illustrating coupled state of FIG. 14;

FIG. 16 is a cross-sectional view taken along line C-C of FIG. 15;

FIGS. 17 and 18 are perspective view and an exploded perspective view ofa sensing magnet and a plate according to a sixth exemplary embodimentof the present disclosure; and

FIG. 19 is a cross-sectional view taken along line D-D of FIG. 18;

DETAILED DESCRIPTION

Advantages and features of the present invention may be understood morereadily by reference to the following detailed description of exemplaryembodiments and the accompanying drawings. Detailed descriptions ofwell-known functions, configurations or constructions are omitted forbrevity and clarity so as not to obscure the description of the presentdisclosure with unnecessary detail. Thus, the present disclosure is notlimited to the exemplary embodiments which will be described below, butmay be implemented in other forms. In the drawings, the width, length,thickness, etc. of components may be exaggerated or reduced for the sakeof convenience. Furthermore, throughout the descriptions, the samereference numerals will be assigned to the same elements in theexplanations of the figures, and explanations that duplicate one anotherwill be omitted.

Accordingly, the meaning of specific terms or words used in thespecification and claims should not be limited to the literal orcommonly employed sense, but should be construed or may be different inaccordance with the intention of a user or an operator and customaryusages. Therefore, the definition of the specific terms or words shouldbe based on the contents across the specification. The terms “a” and“an” herein do not denote a limitation of quantity, but rather denotethe presence of at least one of the referenced item.

As may be used herein, the terms “substantially” and “approximately”provide an industry-accepted tolerance for its corresponding term and/orrelativity between items. Such an industry-accepted tolerance rangesfrom less than one percent to ten percent and corresponds to, but is notlimited to, component values, angles, et cetera.

Now, anti-separating structure of a sensing magnet for EPS motoraccording to the exemplary embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 is a schematic cross-sectional view of an EPS motor according toan exemplary embodiment of the present disclosure.

Referring to FIG. 1, the EPS motor according to the present disclosureincludes a housing (1), and a cover member (2) coupled to an uppersurface of the housing (1) to form a general exterior look of the EPSmotor.

The housing (1) is formed at an inner circumferential surface with astator (4) wound with a plurality of coils, and the stator (4) iscentrally formed with a rotor (5) rotatable by a rotation shaft (3). Arotor core of the rotor (5) may be coupled with a magnet, or the rotorcore and a magnet may be integrally formed. The rotor (5) is formed atan upper surface with a sensing magnet (7) coupled to a plate (6) forobtaining position information of the rotor (5).

The sensing magnet (7) is mounted at an upper surface thereof with amagnetic element (9) to face the sensing magnet (7). The magneticelement (9) is mounted on a PCB (Printed Circuit Board) fixed at aninner surface of the cover member (2). At this time, the magneticelement (9) is preferably provided in a Hall IC.

The characteristic of the present disclosure is a coupling relationshipbetween the plate (6) and the sensing magnet (7), and configurationaccording to a first exemplary embodiment of the present disclosure isdescribed with reference to FIGS. 2 and 3.

The plate (6) according to the first exemplary embodiment of the presentdisclosure is provided in a disk shape, as shown in FIG. 2, and acentral vicinity coupled to the rotation shaft (3) is protrusive formedwith a magnet accommodation unit (6 a) coupled by the sensing magnet(7).

The sensing magnet (7) is provided in a disk shape having an outmostdiameter corresponding to a diameter of the plate (6), centrally formedwith a through hole (7 a) having a diameter corresponding to the magnetaccommodation unit (6 a), and the magnet accommodation unit (6 a) maypass through the through hole (7 a) to be coupled thereto.

Meanwhile, a surface opposite to the sensing magnet (7) of the plate (6)is coated with an adhesive to initially fix the plate (6) to the sensingmagnet (7). In addition to the adhesive, the plate (6) and the sensingmagnet (7) may be adhered using a film member having an adhesivecomponent such as a double-sided tape, if necessary

Referring to FIG. 3, a periphery of a surface passed by the through hole(7 a) of the sensing magnet (7) is preferably formed with magnet gripunits (10) capable of physically gripping the sensing magnet (7), eachat a predetermined gap. The magnet grip unit (10) is preferably deformedto grip the sensing magnet (7) by caulking a periphery of the magnetaccommodation unit (6 a) at a predetermined gap. That is, the caulkingprocess is to generate a plastic deformed portion of the magnetaccommodation unit (6 a) of the plate (6) by applying a predeterminedsize of force to the magnet accommodation unit (6 a), whereby thesensing magnet (7) can be physically gripped.

According to an exemplary embodiment of the present disclosure, themagnet grip unit (10) may be formed by caulking a total of 12 positionsin the periphery of the magnet accommodation unit (6 a) each at a30-degree gap. Furthermore, the caulked magnet grip unit (10) ispreferably formed with spots, each spot sized of approximately 1 mm toobtain a processing convenience. If an excessive broad area is caulkedto form the magnet grip unit (10), the sensing magnet (7) may be damagedduring the caulking process. As a result, as shown in FIG. 1, an upperside of the sensing magnet (7) is inhibited from being physicallyseparated by the magnet grip unit (10) formed by the caulking.

As noted from the foregoing, in addition to the conventional chemicalfixation using an adhesive, the magnet grip unit (10) is providedthrough a caulking process capable of physically gripping the sensingmagnet (7), whereby it is possible to provide a stable coupled structureof the sensing magnet even in a long operation environment, particularlyunder a high temperature.

Particularly, a physical magnet fixing structure is provided by plasticdeformation of a conventionally existing magnet accommodation unit (6 a)of the plate (6) through the caulking process instead of using aseparate sensing magnet fixing member, such that no additional partsexpenses are required and no additional expenditure for material costscaused by increased number of parts is needed.

Referring to FIG. 4, the plate (6) according to a second exemplaryembodiment of the present disclosure is provided in a disk shape, and acentral vicinity coupled to the rotation shaft (3) is protrusivelyformed with a magnet grip unit (10) for inhibiting the sensing magnet(7) from separating. The configuration of the magnet grip unit (10) willbe explained later.

The sensing magnet (7) is provided in a disk shape having an outmostdiameter corresponding to a diameter of the plate (6). The sensingmagnet (7) is centrally formed with a through hole (7 a) of apredetermined diameter whereby the magnet grip unit (10) can be exposednear at the through hole (7 a).

Meanwhile, a surface opposite to the sensing magnet (7) of the plate (6)is coated with an adhesive to initially fix the plate (6) to the sensingmagnet (7). In addition to the adhesive, the plate (6) and the sensingmagnet (7) may be adhered using a film member having an adhesivecomponent such as a double-sided tape, if necessary.

The magnet grip unit (10) includes a support rib (11) and a separationinhibition unit (12). The support rib (11) is protrusively formed at anupper surface of the plate (6), and as shown in FIGS. 4, 5 and 6, atleast one pair of support ribs is provided. However, three or foursupport ribs may be protrusively formed if necessary. Although thesupport rib (11) is formed by preferably punching a portion of the plate(6) and bending a distal end of the punched portion, the method offorming the support rib (11) is not limited thereto, it should beapparent that the plate (6) may be protrusively formed by molding.

Meanwhile, a length of the support rib (11) is greater than a thicknessof the sensing magnet (7), such that more than a predetermined length ofthe support rib (11) can be protruded upwards of the sensing magnet (7),in a case the sensing magnet (7) is inserted while the support rib (11)is erect.

The separation inhibition unit (12) is such that a distal end of thesupport rib (11) is bent to surface-contact an upper surface of thesensing magnet (7). Preferably, in order to allow the lug-shaped erectsupport rib (11) to support an inner circumferential surface of thethrough hole (7 a) of the sensing magnet (7), the sensing magnet (7) iscoupled to an upper surface of the plate (6), a press is used to depressa distal end of the support rib (11) to allow the separation inhibitionunit (12) to surface-contact the upper surface of the sensing magnet(7), as shown in FIGS. 1 and 5. As a result, the upper surface of thesensing magnet (7) is inhibited from physical separation by the magnetgrip unit (10) formed by caulking.

As noted from the foregoing, in addition to the conventional chemicalfixation using an adhesive, the magnet grip unit (10) is providedthrough a caulking process capable of physically gripping the sensingmagnet (7), whereby it is possible to provide a stable coupled structureof the sensing magnet even in a long operation environment, particularlyunder a high temperature.

Particularly, apart from employing a separate sensing magnet (7), theconventionally used magnet grip unit (10) is formed with the plate (6),the sensing magnet (7) is accommodated on the upper surface of the plate(6), a press is used to plastic-deform a distal end of the support rib(11), to form the separation inhibition unit (12) and to provide aphysical magnet fixing structure using the separation inhibition unit(12), whereby no additional parts are consumed, and no additionalmaterial expenditure caused by increased number of parts is needed.

FIG. 7 is a schematic cross-sectional view illustrating an EPS motoraccording to a third exemplary embodiment of the present disclosure.

Referring to FIG. 7, the EPS motor according to the present disclosureincludes a housing (1) and a cover member (2) coupled to an uppersurface of the housing (1), combination of which forms an external lookof the motor.

The housing (1) is formed at an inner circumferential surface with astator (4) wound with a plurality of coils, and the stator (4) iscentrally formed with a rotor (5) rotatable by a rotation shaft (3). Arotor core of the rotor (5) may be coupled with a magnet, or the rotorcore and a magnet may be integrally formed. The rotor (5) is formed atan upper surface with a sensing magnet (7) coupled to a plate (6) forobtaining position information of the rotor (5).

Referring to FIG. 8, the plate (6) is provided in a disk shape and acentral vicinity coupled to the rotation shaft (3) is protrusivelyformed with a magnet support rib (10) to inhibit the sensing magnet (7)from separating. The sensing magnet (7) is provided in a disk shapehaving an outmost diameter corresponding to a diameter of the plate (6),and centrally formed with a through hole (7 a), where an innercircumferential surface of the through hole (7 a) is supported by themagnet support rib (10), the detailed configuration of which will beprovided later.

Meanwhile, a surface opposite to the sensing magnet (7) of the plate (6)is coated with an adhesive to initially fix the plate (6) to the sensingmagnet (7). In addition to the adhesive, the plate (6) and the sensingmagnet (7) may be adhered using a film member having an adhesivecomponent such as a double-sided tape, if necessary.

The sensing magnet (7) is mounted at an upper surface thereof with amagnetic element (9) to face the sensing magnet (7). The magneticelement (9) is mounted on a PCB (Printed Circuit Board) fixed at aninner circumferential surface of the cover member (2). At this time, themagnetic element (9) is preferably provided in a Hall IC.

The characteristic of the present disclosure is a coupling relationshipbetween the plate (6) and the sensing magnet (7), and theanti-separating structure of sensing magnet for EPS motor according toan exemplary embodiment of the present disclosure further includes amagnet support rib (10), a holder member (20) and a fixing unit (30).

The magnet support rib (10) is protruded towards an upper surface of theplate (6), and at least a pair of magnet support ribs (10) is preferablyprovided, as shown in FIGS. 8, 9 and 10. If necessary, three or fourmagnet support ribs (10) may be protrusively formed.

Although the magnet the support rib (10) is formed by preferablypunching a portion of the plate (6) and bending a distal end of thepunched portion, the method of forming the magnet support rib (10) isnot limited thereto, it should be apparent that the plate (6) may beprotrusively formed by molding.

Meanwhile, a length of the magnet support rib (10) is greater than athickness of the sensing magnet (7), such that more than a predeterminedlength of the magnet support rib (10) can be protruded upwards of thesensing magnet (7), in a case the sensing magnet (7) is inserted. whilethe magnet support rib (10) is erect.

Referring to FIGS. 8 and 9, the magnet support rib (10) supports a firstsupport surface (7 b) formed at an inner circumferential surface of thethrough hole (7 a) of the sensing magnet (7). At this time, the firstsupport surface (7 b) is formed at the inner circumferential surface ofthe through hole (7 a) in a shape of a concave portion corresponding tothat of the magnet support rib (10) a concave portion.

A second support surface (7 c) is formed across the first supportsurface (7 b). The second support surface (7 c) is more protruded thanthe first support surface (7 b). However, as shown in the figures, thesecond support surface (7 c) is provided with a surface having a slidingslant to surface-contact a magnet support surface (22) provided at theholder member (20, described later), whereby the sensing magnet (7) isinhibited from separating.

The holder member (20) is coupled to an upper side of the sensing magnet(7) to inhibit the sensing magnet (7) from separating from the plate(6). The holder member (20) is secured to the plate (6) by the fixingunit (30). The holder member (20) is provided in a thin metal plate ofan elastic material to be elastically deformed when fastened to afastening member (30, described later), where the sensing magnet (7) canbe depressed by elastic restoring force of the holder member (20).

The holder member (20) includes a rib groove (21) supporting a lateralsurface of the magnet support rib (10), and a magnet support surface(22), and is centrally formed with a void space through which the plate(6) is exposed.

The rib groove (21) supports the other surface of the magnet support rib(10) surface-contacting the first support surface (7 b), and is formedto have a shape of a concave portion corresponding to that of the magnetsupport rib (10) like the first support surface (7 b). The rib groove(21) is preferably formed at a position opposite to the magnet supportrib (10) of the holder member (20), such that in a case a pair of magnetsupport ribs (10) is provided, it is preferred that the rib groove (21)be also provided in a pair.

The magnet support surface (22) serves to surface-contact the secondsupport surface (7 c) and it is preferred that the magnet supportsurface (22) be formed across the rib groove (21) as wings of a body ofthe holder member (20).

That is, as shown in the figures, the rib groove (21) may be formed inthe shape of a concave groove relative to the magnet support surface(22). The magnet support surface (22) is provided in a bent shape at apredetermined angle relative to the body of the holder member (20), suchthat the sensing magnet (7) can be depressed and secured to the plate(6) side when fastened by the fixing unit (30, described later).

As mentioned above, the magnet support surface (22) serves tosurface-contact the second support surface (7 c) of the sensing magnet(7) to inhibit the sensing magnet (7) from separating from the plate(6).

The present disclosure provides a total of three exemplary embodimentsthat are classified according to configuration of the fixing unit (30),details of which is provided hereunder.

In a third exemplary embodiment of the present disclosure, the fixingunit (30) includes a fastening screw (31) fastened to a second throughhole (33) penetratively formed at the plate (6) after passing through afirst through hole (32) penetratively formed at the holder member (20).At this time, the first through hole (32), as shown in FIG. 2, maycommunicate with a central space of the holder member (20).

Referring to FIGS. 9 and 10, the configuration thus mentioned caninhibit the sensing magnet (7) from separating because the holder member(20) is fastened to the plate (6) by the fastening screw (31).

Referring to FIGS. 11, 12 and 13, and in comparison with the thirdexemplary embodiment of the present disclosure, the fixing unit (30)according to a fourth exemplary embodiment of the present disclosure issuch that the fastening screw (31) is replaced with a rivet (31′), andthe first through hole (32) penetratively formed in a groove shape inthe first exemplary embodiment is replaced with a first through hole(32′) formed in a penetrative round through hole as shown in FIG. 5 tosecure the holder member (20) in a sturdier manner than that of a headof the rivet (31′).

According to the rivet coupling based on the second exemplary embodimentof the present disclosure, there happens no problem of letting theholder member (20) separate from the plate (6) due to the loosened screwfastening during a long time of use.

Meanwhile, referring to FIGS. 14, 15 and 16, a fastening unit (30′)according to a fifth exemplary embodiment of the present disclosureincludes a hook (35) integrally formed with the holder member (20) and ahitching unit (36), unlike the fastening screw (31) or the rivet (31′)as in the third and fourth exemplary embodiments of the presentdisclosure.

The hook (35) is integrally formed with the holder member (20) and isprotrusively formed toward the plate (6) from the holder member (20).The hook (35) is preferably formed by bending a portion extended to adirection of the other side of the magnet support surface (22) from therib groove (21) of the holder member (20) as shown in FIGS. 14, 15 and16. As a result, the rib groove (21) surface-contacting the magnetsupport rib (10) in the third and fourth exemplary embodiments of thepresent disclosure becomes a bending point of the hook (35) that no moresupports the magnet support rib (10) in the fifth exemplary embodimentof the present disclosure.

The hitching unit (36) may be provided in a separate through hole, butit is preferred that a portion penetratively formed at the plate (6) beused as the hitching unit (36) for formation of the magnet support rib(10) as illustrated in FIGS. 15 and 16.

According to the abovementioned configuration and as depicted in FIG.16, the holder member (20) can fix and hook the integrally formed hook(35) to the hitching unit (36) without recourse to a separate fasteningmember such as the fastening screw (31) or the rivet (31′) as describedin the first and second exemplary embodiments of the present disclosure.

As noted from the foregoing, in addition to the conventional chemicalfixation using an adhesive, the holder member (20) can be fixed usingvarious types of fixing units (30) capable of physically gripping thesensing magnet (7), whereby it is possible to provide a stable coupled.structure of the sensing magnet even in a long operation environment,particularly under a high temperature.

Meanwhile, according to a sixth exemplary embodiment of the presentdisclosure, an adhesive accommodation groove (7 d) may be formed at apredetermined depth on a surface opposite to the plate (6) of thesensing magnet (7). The adhesive accommodation groove (7 d) is providedin a shape of a ring having a diameter smaller than that of the sensingmagnet (7) as shown in FIG. 18, and as illustrated in thecross-sectional view of FIG. 19, the adhesive accommodation groove (7 d)is preferably formed with a predetermined depth (d), preferably notexceeding 0.05 mm. If the depth (d) is too deep, strength of the sensingmagnet (7) may be weakened to increase an amount of injected adhesive.

Meanwhile, the adhesive accommodation groove (7 d) may be so arranged asto inhibit a formed position of a main magnet (M1) from interfering witha formed position of a sub magnet (M2), as depicted in FIG. 17, suchthat magnetized patterns of the main and sub magnets (M1, M2) are notaffected.

In a case the adhesive accommodation groove (7 d) is formed at thesensing magnet (7), there is no need of performing a pressing process ofspreading an adhesive to a surface opposite to the plate (6) of thesensing magnet (7) to dispense with the fear of damaging the sensingmagnet (7) in the pressing process, and to reduce the manufacturing costas a constant amount of adhesive can be used at all times.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims.

What is claimed is:
 1. An anti-separating structure of a sensing magnetfor an EPS motor, the structure comprising: a disk-shaped platecentrally inserted by a rotation shaft; a ring-shaped sensing magnethaving a through hole at a center coupled to an upper side of the plate,formed with a main magnet at a position near to a periphery and formedwith a sub magnet at a position near to the through hole; a magnetsupport rib protruded from the plate toward sensing magnet to grip aportion of the through hole at the sensing magnet; a holder memberinserted into the through hole and coupled to an upper side of thesensing magnet; a fixing unit fixing the holder member to the plate; andan adhesive accommodation groove formed at a predetermined depth on asurface opposite to the plate of the sensing magnet and coated thereinwith an adhesive.
 2. The structure of claim I, wherein the fixing unitincludes a fastening member coupled to a second through holepenetratively formed at the plate after passing through the firstthrough hole penetratively formed at the holder member.
 3. The structureof claim 2, wherein the fastening member includes any one of a screw ora rivet.
 4. The structure of claim I, wherein the adhesive accommodationgroove is so arranged as to inhibit a formed position of the main magnetfrom interfering with a formed position of the sub magnet.
 5. Thestructure of claim 1, wherein the adhesive accommodation groove isformed with a depth within 0.05 mm.
 6. The structure of claim 1, whereinan outmost diameter of the sensing magnet corresponds to a diameter ofthe plate.
 7. The structure of claim 1, wherein the ring-shaped sensingmagnet includes a first support surface in the through hole and a secondsupport surface protruded adjacent the first support surface.
 8. Thestructure of claim 7, wherein the second support surface is protrusivelyformed at both sides of the first support surface and toward a center ofthe sensing magnet.
 9. The structure of claim 8, wherein two firstsupport surfaces are provided facing each other and symmetrically formedbased on the center of the sensing magnet, and wherein two secondsupport surfaces are provided facing each other and symmetrically formedon the center of the sensing magnet.
 10. The structure of claim 8,wherein the second support surface is formed with a slant surface of apredetermined area to allow surface-contacting a surface opposite to theholder member.
 11. The structure of claim 1, wherein the adhesiveaccommodation groove is formed in a shape of a ring.
 12. The structureof claim 11, wherein a diameter of the adhesive accommodation groove issmaller than that of the sensing magnet plate.
 13. The structure ofclaim 1, wherein each first support surface is formed in a shape of aconcave portion corresponding to that of the magnet support rib.
 14. Thestructure of claim 1, wherein the holder member includes a rib groovesupporting a lateral surface of the magnet support rib, and wherein therib groove is formed at a mid-portion of the magnet support surface. 15.An EPS motor having the anti-separating structure of claim 1, the EPSmotor comprising: a housing; a stator disposed in the housing and woundwith a coil; and a rotor centrally formed in the stator and rotatable bythe rotation shaft.
 16. The EPS motor of claim 15, further comprising acover member coupled to an upper surface of the housing.
 17. The EPSmotor of claim 15, wherein the fixing unit includes a fastening membercoupled to a second through hole penetratively formed at the plate afterpassing through the first through hole penetratively formed at theholder member.
 18. The EPS motor of claim 15, wherein the ring-shapedsensing magnet includes a first support surface in the through hole anda second support surface protruded adjacent the first support surface.19. The EPS motor of claim 18, wherein the second support surface isprotrusively formed at both sides of the first support surface, andwherein the second support surface is formed with a slant surface of apredetermined area.